Size and weight are big decision factors when you are trying to find the ideal camera for your needs.
In this section, we are going to illustrate the Panasonic GF3 and Sony W710 side-by-side from the front, back and top in their relative dimensions. Panasonic GF3 has external dimensions of 108 x 67 x 32 mm (4.25 x 2.64 x 1.26″) and weighs 264 g (0.58 lb / 9.31 oz) (including batteries). Sony W710 has external dimensions of 97 x 55 x 20 mm (3.82 x 2.17 x 0.79″) and weighs 114 g (0.25 lb / 4.02 oz) (including batteries).
Below you can see the front-view size comparison of the Panasonic GF3 and the Sony W710. Sony W710 is clearly the smaller of the two cameras. Its body is 11mm narrower, 12mm shorter and 12mm thinner than Panasonic GF3. As you can tell, actually this is not a fair size comparison since Sony W710 has a built-in lens but Panasonic GF3 doesn't. Once you put a lens on GF3, its thickness will increase significantly.
Here is the back view size comparison of the Panasonic GF3 and Sony W710.
Weight is another important factor, especially when deciding on a camera that you want to carry with you all day.
Sony W710 is significantly lighter (150g ) than the Panasonic GF3 which may become a big advantage especially on long walking trips.
Again, this comparison may not be very useful in real life as we are comparing the weight of a camera with a built-in lens to the body-only weight of an interchangeable lens camera. Once you put a lens on GF3, the total kit will weigh much higher.
Weather Sealing
Unfortunately neither the Panasonic Lumix DMC-GF3 nor Sony Cyber-shot DSC-W710 provides any type of weather sealing in their bodies, so you have to give extra care especially when you are shooting outdoors. If weather sealing is a must-have feature for you, check these sections: Top Mirrorless Cameras with Weather Sealing Top Compact Cameras with Weather Sealing
LCD Screen Size and Features
Panasonic GF3's 3.00" LCD screen is slightly larger than Sony W710's 2.7" screen.
Unfortunately, both cameras has fixed screens so they don't tilt or flip in directions.